Physicians


Meet your team! Our greatly experienced and board-certified doctors specialize in all aspects of kidney disease. We have all pledged and dedicated ourselves to providing the highest quality and personalized kidney care while building long-term partnerships with patients, their families, and their other healthcare providers.

Jeannie Co, M.D.


Doctor Co is a board-certified nephrologist and joined Columbus Nephrology, Inc. in February 2022, though she has been a well-known and trusted member of the Central Ohio nephrology community for several years. She received her medical degree from The University of Philippines College of Medicine. She completed her internal medicine/pediatrics residency at West Virginia University and nephrology training at Allegheny General Hospital

Chakravarthi Ramaswamy, M.D.


Doctor Ramaswamy is a board-certified nephrologist and immediate past President of Columbus Nephrology, Inc. He received his degree from Kilpauk Medical College. In addition to extensive medical training and research in Great Britain, he completed internal medicine residency at Long Island Hospital in New York and fellowship in nephrology at Vanderbilt University.

Kevin O’Reilly, M.D.


Doctor O’Reilly is a board-certified nephrologist and current President of Columbus Nephrology.
He graduated from The Ohio State University Colleges of Pharmacy and Medicine. He completed his internal medicine residency and nephrology fellowship at the University of North Carolina-Chapel Hill.

Paul Kovach, M.D.


Doctor Kovach is board-certified nephrologist. He graduated from the University of Notre Dame and Case Western Reserve University Medical School. He completed his internal medicine residency and nephrology fellowship at Washington University in St Louis.

Nicholas Stoycheff, M.D.


Doctor Stoycheff is a board-certified nephrologist. He received his undergraduate and medical degrees at The Ohio State University. He completed his internal medicine residency at the University of Maryland. He completed a master of science in clinical research and his nephrology fellowship at Tufts Medical Center in Boston. After fellowship, he trained in radiology-based procedures of dialysis vascular access and currently works both taking care of people with general kidney problems as a general nephrologist and performing procedures as an interventional nephrologist.

Ravish Shah, M.D.


Doctor Shah is a board-certified nephrologist. He received his medical degree from Dr. D.Y.Patil Medical College, Mumbai, India. He completed his internal medicine residency at the Southern Illinois University and his nephrology fellowship at The Ohio State University where he also received extensive training in radiology-based procedures of dialysis vascular access. Following fellowship, he served on the faculty at Ohio State, practicing both general and interventional nephrology. He joined Columbus Nephrology in July 2014.

Vahagn Zakaryan, M.D.


Doctor Zakaryan is a board certified nephrologist. He received his medical degree from Yerevan State Medical University, Armenia. He completed his internal medicine training at Mount Carmel Health System in Columbus, Ohio. During his nephrology fellowship training at The Ohio State University, he was unanimously chosen by the faculty as the most distinguished nephrology fellow for 2 years. Dr. Zakaryan joined Columbus Nephrology in 2017.

Stephen Roderer, M.D.


Doctor Roderer is a board-certified nephrologist from Centerville, Ohio. He completed medical school and internal medicine and nephrology training at The Ohio State University.

Sefenesh Mamai, CNP


Certified Adult-Gerontology Acute Care Nurse Practitioner. Graduated with a Bachelor of Science in Nursing and Master of Science from Mount Carmel College of Nursing.